The invention relates to an insert filter for cleaning a gas stream, which is replaceably positioned in a shaft of a duct system through which the gas stream is guided, and which comprises a filter frame, a filter element supported by the filter frame, and a shaft cover for closing an opening through which the filter is inserted into the shaft.
A filter, accommodated by an adapter, which is inserted in a shaft of a channel of a ventilation or air-conditioning unit is known from DE 42 34 047. The shaft is closed with a cover and clamped with clamps. The clamps can be displaced on locking bars. The locking bars are located both on the cover and on the channel. The filter has a filter frame, three sides of which are inserted in the shaft, with the cover forming the fourth side of the filter frame and also being inserted in the shaft. The shaft is constructed in such a way that it tapers continuously beginning at an insertion side, so that the force necessary to insert the filter is low and seals only come to bear against the filter when it is completely installed. The seals, which lie opposite the insertion side, are pressed firmly against the shaft when the cover is locked with the shaft.
To remove the filter from the shaft, the clamps must first be pushed aside. Subsequently, a pull is necessary, which pulls the filter out of the shaft. However, in order to transmit this pull to the filter, an additional removal aid is necessary because the cover itself is not positioned in the shaft in such a way that it can be readily grasped. This removal aid is thus absolutely necessary for every replacement of the filter. The use of an additional removal aid is, however, troublesome and if the removal aid is lost, the filter cannot be replaced.
Accordingly, it is an object of the invention to provide an insert filter, which can be placed in a shaft of a duct system for guiding gas flow, such that the insert filter can be removed from the shaft without additional removal aids.
This and other objects are achieved in accordance with the present invention by providing an Insert filter for cleaning a gas stream, which is replaceably positioned in a shaft of a duct system through which the gas stream is guided such that the filter separates an unfiltered side from a clean side, the filter comprising a filter frame, a filter element supported by the filter frame, and a shaft cover, wherein the shaft cover is constructed separately from the filter frame and attached thereto, and wherein the filter frame is removable from the shaft exclusively by using the shaft cover.
The insert filter according to the invention is positioned in the shaft of a duct system for guiding a gas stream and serves to purify a gas stream. The duct system can, for example, guide intake air for an internal combustion engine, ventilation air for a clean room, or another gas for a gas consumer. The insert filter is formed by a filter frame, a filter element supported by the filter frame, and a shaft cover connected with the filter frame, with the filter element able to be formed by a filter medium with a border or by a filter medium alone, such as a non-woven fabric or paper.
Furthermore, the filter frame may be comprised of a great variety of materials such as nonwoven webs, thermoplastic, or metal. The insert filter is placed in the shaft in such a way that it separates an unfiltered side from a clean side.
Depending on the filter element with its filter unit, a leakage airflow between the insert filter and the shaft may or may not be permissible. For a coarse filter element, which only filters out coarse impurities, a certain leakage airflow is permissible. For a fine filter element, such as for clean rooms, no leakage airflow is acceptable. In this case, a seal is to be provided between the insert filter and the shaft which, for example, can be positioned on the shaft.
The filter frame, which is completely inside the shaft, is connected with the shaft cover so that the insert filter can be removed from the shaft without an additional removal aid. For this purpose, the side of the filter frame facing the shaft cover can be constructed as taller than the other sides. In this way, a larger connection surface is available for attachment of the shaft cover to the filter frame. The shaft cover is constructed in such a way that it can be easily grasped for replacement of the insert filter. This can be achieved by, for example, a bulge or recesses. The connection existing between the filter frame and the shaft cover is constructed in such a way that the pull necessary for removal of the insert filter from the shaft can be transmitted. The shaft can run partially or completely at a slant in the direction from the top of the shaft to the bottom of the shaft, thereby making introduction of the insert filter into the shaft easier.
The shaft cover can be attached removably or permanently to the filter frame. In this regard, a permanent connection can be produced by, for example, gluing or welding. Removable connections between the shaft cover and filter frame can be formed by positive fits or non-positive fits. For this purpose, screws, hooks, clamps, springs, or fits, for example, can be used. Furthermore, the shaft cover can be inserted in a receiver groove on the filter frame. In other embodiments, the receiver groove can also be positioned on the shaft cover.
The shaft cover can have fastening means available with which the shaft cover is connected with the shaft, so that uncontrolled detachment of the insert filter from the shaft is prevented. Screws, catches, or frets can, for example, serve for this purpose.
According to a further embodiment of the invention, the connection between the filter frame and the shaft cover is constructed so as to be separable. In this way, the shaft cover can be separated from the filter frame after the filter frame is removed from shaft. This is particularly advantageous for replaceable filters in which the filter frame and the filter element must be disposed of, because the shaft cover can be used again. The use of snap hooks to connect the filter frame with the shaft cover represents an advantageous solution, because no additional fastening means are necessary, so that assembly time and expense can be minimized. The shaft cover is snapped onto the filter frame, with the snap hooks springing back and holding the filter frame together with the shaft cover in the assembled state.
It is advantageous to provide an integrated removal aid on the shaft cover, whereby the pull necessary for removal can be better transmitted to the shaft cover. This integrated removal aid can, for example, be formed by an lifting strap, a grip hollow, or a handle. The handle can have one or more attachment points available on the shaft cover, whereby greatly varying embodiments such as a knob or a bow are conceivable.
A further variant of the invention provides a cover seal between the shaft cover and the shaft. This cover seal prevents the entrance of external gases or the escape of gases carried in the duct system and can be connected with the shaft cover or the shaft by, for example, being glued, clipped, or molded on. It is, however, also conceivable that the cover seal is placed loosely between the shaft and the shaft cover and, after the insert filter is completely inserted in the shaft, is pressed between the shaft and shaft cover. Furthermore, however, the cover seal can also be produced through the application of suitable materials such as silicone or adhesive between the shaft cover and the shaft.
A further variant of the invention has a peripheral frame seal on the filter frame which supports itself on the shaft. This frame seal is comprised of a material which has sealing properties, and for this purpose the frame seal can be formed of the same material as the filter frame or of some other material. The frame seal can be inserted loosely in, for example, a groove on the filter frame or, for example, be permanently connected with adhesive or by two-component injection molding with the filter frame. Furthermore, the frame seal can be constructed in various ways. One possibility provides for the use of a sealing lip which presses against the shaft when the filter frame is inserted into the shaft. Another possibility for implementing the frame seal is to position multiple small lamellae which press against the shaft.
It is advantageous to position a crossbrace on the filter frame to stabilize the filter element. This crossbrace can be formed by a lengthwise strut and a transverse strut, which offer the filter element support against sagging caused by the gas stream. Further embodiments having multiple lengthwise and/or transverse struts are conceivable. This crossbrace can, for example, be clamped in the filter frame or screwed onto it.
One particular embodiment of the connection of the crossbrace with the filter frame is a spring-groove connection, in which a specially constructed spring on the crossbrace engages in a groove in the filter frame, thereby fixing the filter element. This connection can, for example, be detached when the filter element is replaced and subsequently be produced again.
A specific embodiment of the invention is formed by the filter frame having a frame wall which encloses a filter region in which the filter element is inserted. In this embodiment, the filter element can, for example, be formed by a non-woven filter web, an activated carbon filter, a filter paper, or a felt, with this filter medium also able to be folded. The frame wall extends diagonally to (i.e. is slanted toward) the filter region, so that the inserted filter element is compressed in a lower peripheral region close to the frame wall. This compression of the filter element reduces the leakage between the filter frame and the filter element. For improved fixing of the filter element, the crossbrace can press the filter element deeper into the filter frame.
According to a particular embodiment of the invention, the insert filter according to the invention is intended as an air filter for an internal combustion engine. In the ever tighter spatial relationships in the engine compartment of a motor vehicle, a filter housing can hereby be conceived which can be opened at the top through the cover to replace the filter element. Therefore, no removal space is necessary for the filter element within the engine block. Rather, the filter element can be removed upward, i.e., in the direction where the filter housing abuts the engine hood. It is particularly advantageous to position a filter housing on both the right and the left of the engine block. In this case, further casings can connect these two filter housings with one another, whereby noise dampening can additionally be produced. In addition, the positioning of the filter elements on both sides further serves for optimal air distribution, for example for a combustion engine with a V-shaped layout of the cylinders.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or in the drawings, and the individual features each may be constructed in embodiments of the invention either individually or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.